Device for photographic survey from aircraft



July 7, 1936. n E, HRNER 2,047,070

DEVICE FOR PHOTOGEAPHIQ SURVEY FROM AIRCRAFT Filed April 20, 1933 2Sheets-Sheet l @www 'A fr0/#wey July 7, 1936'.

E. HRNER 2,047,070

DEVICE FOR PHOTOGPHIC SURVEY FROM AIRCRAFT Filed April 20, 1933' a.sheets-sheet 2 I Affe/wey Jlwezeir:

Patented July 7, 191,36

UNITED STATES PATENT OFFICE FROM AIRCRAFT Erich Hrner, Berlin, GermanyApplication April 20, 1933, Serial No. 66?;121 In ,Germany February 22,1927 'I'his invention relates to an apparatus for the photographing ofterritory from aircraft, particularly for surveying purposes forwhichapplication has been filed in Germany on February 22, 1927.

graphs from an aircraft 'of' the territory to be surveyed, from pointsat certain distances apart, which photographs partly overlap.' In thispro- 10 cedure each pair of successive pictures forms a stereoscopicphotograph of that territorial area which is represented on the twoplates. In mapping the survey, this stereoscopic picture is placed in astereoscopic projector to produce an optil5 cal model of thephotographed area, and from this model the map is drawn or a relief canbe prepared.

In this utilization of stereoscopic photographs it is important to notethe position in space of each plate at the instant of exposure and itsoptical and physical inclination in orders; that the pictures can bebrought into exactly the same position in the projector. It is knownthat aircraft are subject to continuous deviations in flight so that thephotographic plate or film at the instant of exposure in general doesnot lie-in a horizontal plane; also the inclinations of all the platesvary from each other. y The present invention has for its object toproso vide an apparatus permitting the position of each plate to theoptico-physical level at the instant of exposure to be recorded on theplate itself in such a manner that this position can be reproduced inthe stereoscopic projector with the plate oriented as in its naturalposition in space.

It has already been proposed in order to determine the exposure positionof survey photographs taken from aircraft, to record the position ofindicators, ras for example those oiv clinometersA or pendulums,compasses, elevation barometerasun-position indicators, simultane-'ously with the exposure. I

If the exposure date (for example fore and aft i inclination, transverseinclination, etc.) are lL5 known, (for example by recording the readingsof instruments) then the nadir image can be obtained graphically or bycalculation, and the first adjustment in the mapping apparatus performedwith the aid of this nadir image. Howjreduce these operations and torender territorial surveying more economical than heretofore. 'I'heinvention is carried out in such a way that its horizontal position.

each photographing of a territorial area, but independently thereof',the indication. of the point is photographed, which then can be directlytransferred to the territory photograph. In applying this method thereis employed an vappa- 5 In territorial surveys it is knownl to takephotoratus which indicates the position in space of the plate exposedand photographically determines this position.

The apparatus consists of a clinometer instrument operating by gravity,to wit, a spirit 10 level, with.which a sun-dial device cooperates insuch a manner that it throws the shadow of a spot on the dial of thelevel, which shadow lmaintains the same distance from` the axis of theclinometer instrument during the whole expo- 15 sure as long as theinstrument-does not change The position of the shadow and otherindications of the clinometer are photographed on a separate plate sothat they can be lexactlyand clearly recognized. The 20 photographiccamera'used for this purpose has the same width of iield as the camerafor photographing the territory.

The accompanying drawings illustrate by wayof example apparatusembodying the invention. Inthese drawings: r

Figure 1 is a sectional view of the entire apparatus. f

Fig. 2 is a top view partly in section of the apparatus.

Fig. 3 is a sectional view taken on line 3 3 of F18. 2.

Fig. 4 represents a photograph of the indicating means.

The camera I serves the purpose of photo- 35 graphing the ground orlandscape and the camera 2 is for the purpose ofphotographing Ytheindications for instrument readings. Both cameras l and 2 will have thesame picture widths and are so coupled with each other that theirlongitudinal axis will alwaysbe parallel to each other. Above the camera2, there is provided as a clinometer device, two spirit levels 3 and 4of diiIerent inertias in which each has an air bubble 3a and 4a whichhave different rapid move- 45 ments whenl the levels swing out of theirpositions of rest. Above the spirit levels, there is a sun dial device.The latter consists of a glass plate 5 with a shadow projecting means asfor examp1e the black point s which in the vertical 50 position will liein the axis of the spirit levels. The plate 5 is carried by a plate 1which as will be further described isv adjustable in 4accordancewith theposition of the sun. By'this construction the result is tobe attainedthat the shadow 55 Amiddle point oi the plate or surface 9. By rotat-sing the apparatus, which can be eiIected automatically by a compass,otherwise manuallybymeans oi the actuator I0, the shadow can .alwaysbekept on one and the same pointion the plate 9 notwithstanding rotationoi the apparatus.

Each time that the camera I takes a. picture the camera;` 2 will at 'thesame time photograph the spiritlevels and the sun dial device on vaplate or film Ii Fig. 4 represents a photograph, some.

what enlarged, of a picture as taken by the camera 2. 'Ii the plate IIand therewith also the vplate ofl the camera I were absolutelyhorizontal at the time of taking pictures then the photograph inaccordance with Fig. 4 would show the bubbles of the spirit levelsexactly in the center A and the shadow 8 will be the point 8a. However,if the photographic plates lare not horizontal due-to the angularposition of an airplane,

for instance, then the air bubble 3a will be shifted` to 3b, andthe airbubble la to 4b and the shadow ,3&0 8 tob, Fig. 4. 'Ihe center pointwould then lie in the point I2 and in a similar manner the.

photograph taken by the camera] can be transposed. It is, however,possible that an airplane may be'ying in a plane far on Strom thehorizontal so that camera I would then make an unusable picture. Inorder to prevent the foregoing, the following arrangement is utilized.

, A mirror I3 is provided above the camera 2 which permits the rayscoming from the spirit levels to pass therethrough `to the camera 2 aswell as to throw the rays 4that is a representation l of the spiritlevels and the sun dial device' under the observation plate I5 overwhichthere is provided indicator I5. The breaking oi the rays passingthrough the mirror I3 is`compensated for -by the provision of a glassplate lia in the camera 2. The indicator I6 is secured to a lever androd arrangement l1, the latter of which is cou` pled to the cameras land 2. Camera I can swing around its center point of the objective I8and the camera, 2 can swing around the center point of its objective is;Now, if an observer notes that the position of the air bubble oi thespirit levels and the shadow of the sun dial device relative to the.indicator 'I6 will result in an unusable photograph due to the airplaneflying in a nonhorizontal position the observer will then operate i thelever and rod arrangement I1 by means of its handle in order to adjustthe cameras I.. and 2 5 before actually taking the picture so that' thelongitudinal axes oi' the cameras I andy 2 will be in their properpositions. v

The sun dial/device is operated by achronometer 2l arranged in thecasing '20. To the plate 1,

5 Arods 22 are secured which are carried by shafts 23. (Dnthe shafts 23are located small gear wheels 24 which mesh with stationary toothedquadrants 25 so that plate I can always be' adjusted in a parallelrelation. Rods 28 are also secured to the 0 pme 1 and these mds havebent ends projecting into the arcuate recesses 21'ofthe plates 28.

Theplates 23 are curved and the arcuate recesses z 21 corresponding incurvaturewith the' path of the sun. The chronometer 2| can rotate the 7gears' Non theirtracks 25 by means of the rods asse/,ove

29 and 35 which are connected with the shaft 23.

f Now, if the chronometer 2| has adjusted the rod 30 in a position asfor example indicated by the dot and dash line 30a, the plate 1 will notalone be moved tothe right but it will assume a 5 somewhat lowerposition as indicated by the dot and dash lines 1a. In this position therods 23 are also moved down to the position indicated by k the dot anddash linea, Fig. 3, so that the plate 1 finally willbe moved into theposition shown -10 in Flg.'2 by the dot and dash line 1a. In this waythe point 6 will be moved over to point 3a rso that Iits shadow willalso be adjusted so that the shadow will likewise fall on the point l onthe surface 'or plate 9. 15

. vThe indicator 2Ia o! the chonometer 2l will be moved over a ring'formed dial 2lb. The casing 20 also contains other instruments, namely,

a compass 3l, of which its indicator 3Ia also moves over aring formedgraduated member 3 Ib, 20 'further a barometer, with an indicator 32awhich likewise moves over a ring 'formed graduated member 321i,Y andfinally a numeral device 33, oi known type, which is operated by thechronometer 2l. The graduated ring formed de- 25 vices 2lb, 3Ib and B2band the positions of-the dials 2m, 3Ia and 32a will be thrown on theplate oi'. the camera 2 by means oi the mirrors 3l and 35. The mirror 35is only in the shape or a ring so that the rays coming from the spiritleven 3 can uninterruptedly pass therethrough to the camera 2. 0n thetaking of each picture of thc spirit levels and the sun dial compass,there will be taken at the same time-the indications on the members 2lb,3Ib and 32h so that on the photo- 35 graph as shown in Fig. 4, themiddley part show the positions of the spirit ,level bubbles and aroundthese will appear the rings 2lb, 3Ib and 32h together with the dialYpositions ol' the indicators 2Ia, 3Ia, land 32a. By means of the part 433 thenumber of the photograph will also be recordedthereon from thenumeral device.

I claimas my invention:

' 1. Apparatus for use in aerial photographi surveying, comprising acamera for photograph- 45 ing territory. a clinomter devicewith'indicating l means, a camera so aligned with the clinometcr deviceas Ito be able to photograph itsdndications, said camera having apicture width similar to 5o that of the survey camera, and meansconnecting the two cameras for holding their focal axes parallel. v e

2,. Apparatus according to claim 1, in whichthc clinometer devicecomprises at least two super- 55 posed spirit levels of diii'enentinertlras.

,13. Apparatus for use in aerial photographic surveyfng, comprising acamersi'or photographing. territory, a clinometer device with indicating-means a camera so aligned with the clinometer device as to be able tophotograph its indications, saidf camera having a picture widthsimilar`to that or the survey camera, ,a sun-dial .device adapted tothrow a spot shadow on the indicating means oi' the clinometer device,and means 65 for moving the shadow-throwing spot of the sundial devicerelatively to sol movement that the spot shadow remains statigary withrespecfto the clinometer indicating means asl long as the, cilnometerdevice remains'-horizontal.^ 7 0 4. Apparatus according to claim 3,comprising also a compass adapted tocontrol the apparatus includingtleclinometer. s

5. Apparatus according .to claim 3 in which a compass is providedadapted 'tocontrol the appa- 75 ratus and an optical system comprising acentrally apertured mirror arranged with its aperture aligned with thefocal axis of the clinometer camera and the ciinometer and adapted tothrow an image of the compass dialv into said camera concentrically withthe image of the ciinometer indicating means.v

6. Apparatus for use in aerial photograph surveying comprising a camerafor photographing territory, a clinometer device with indicating means,a camera. so aligned with the clinometer device .as to be able tophotograph its indications,

said camera having a. picture width similar to that oi the surveycamera, a sun-dial device adapted to throw a spot shadow on theindicating means of the ciinometer device, means for moving theshadow-throwing spot of the sun-dial device relatively to solar movementthat the spot shadow remains stationarywith respect toi the clinometerindicating means as long as the clinometer device remains horizontal, asemi-reflecting and semi-'transparent disk in /tront of the clinometercamera, anda screen to throw an 5 image of the clinometer indicatingmeans on the screen by the disk.

7. Apparatus according to claim K6, comprising also an indicator movableover the screen and connected to the territory photographing camera 41oand the ciinometer camera.

' .8. Apparatus according to claim 3 in which the clinometer camera andthe territory photograph ing camera have means for making correspondingcoordinate survey marks on the pictures 15 taken thereby.

t Enron Homann..v

